Two-stage catalyst for removal of NOx from exhaust gas stream

Patent metadata

Field	Value
Publication number	US-10857504-B2
Application number	US-201916435773-A
Country	US
Kind code	B2
Filing date	Jun 10, 2019
Priority date	Mar 31, 2017
Publication date	Dec 8, 2020
Grant date	Dec 8, 2020

Abstract

A co-catalyst system for the removal of NO x from an exhaust gas stream has a layered oxide and a spinel of formula Ni 0.15 Co 0.85 CoAlO 4 . The system converts to nitric oxide to nitrogen gas with high product specificity. The layered oxide is configured to convert NO x in the exhaust gas stream to an N 2 O intermediate, and the spinel is configured to convert the N 2 O intermediate to N 2 .

First claim

What is claimed is:

1. A catalytic converter for the removal of NO x from an exhaust gas stream operating between 350 and 550° C., the catalytic converter comprising:
an inlet configured to receive the exhaust gas stream into an enclosure;
an outlet configured to allow the exhaust gas stream to exit the enclosure; and
a co-catalyst system contained inside the enclosure, the co-catalyst system having:
a layered oxide having a formula La 2-x M x QO 4 , for catalyzing a reduction reaction of at least one of NO and NO 2 to generate N 2 O wherein:
M is a cationic metal selected from the group consisting of: Ca, Sr, Ba, and a combination thereof;

Q is a cationic metal selected from the group consisting of: Fe, Ni, Co, and a combination thereof; and
a spinel having a formula, Ni y Co 1-y CoAlO 4 , wherein y is a value within a range of about 0.1 to about 0.9, inclusive, for catalyzing a decomposition reaction of N 2 O to N 2 .

2. The catalytic converter according to claim 1 , wherein the co-catalyst system is configured as a sequential co-catalyst and the exhaust gas stream moves in a flow direction, with the layered oxide being positioned upstream of the spinel structure relative to the flow direction.

3. The converter according to claim 1 , further comprising a separation space between the first chamber and the second chamber.

4. The catalytic converter according to claim 1 , wherein the co-catalyst system is configured as a mixed co-catalyst in which the layered oxide and the spinel are substantially intermixed.

5. The catalytic converter according to claim 1 , wherein the layered oxide comprises LaBaCoO 4 .

6. The catalytic converter according to claim 1 , wherein the layered oxide comprises LaBaFeO 4 .

7. The catalytic converter according to claim 1 , wherein the layered oxide is in a nanoparticle form, of 2 to 50 nm in diameter.

8. The catalytic converter according to claim 1 , wherein the spinel has a formula, Ni 0.15 Co 0.85 CoAlO 4 .

9. The catalytic converter according to claim 1 , wherein the spinel is in nanoparticle form, of 2 to 50 nm in diameter.

10. A two-stage method for the removal of NO x from an exhaust gas stream, the method comprising:
flowing the exhaust gas stream through a co-catalyst system comprising:
exposing the exhaust gas stream to a layered oxide and catalyzing a reduction of at least one of NO and NO 2 to generate N 2 O, the layered oxide having a formula La 2-x M x QO 4 , wherein:
M is a cationic metal selected from the group consisting of: Ca, Sr, Ba, and a combination thereof;
Q is a cationic metal selected from the group consisting of: Fe, Ni, Co, and a combination thereof; and
x is within a range of from about 0.01 to about 1.5, inclusive; and

contacting the exhaust gas stream with a spinel having a formula Ni y Co 1-y CoAlO 4 , wherein y is a value within a range of about 0.1 to about 0.9, inclusive, to decompose the N 2 O to N 2 .

11. The method as recited in claim 10 , wherein the layered oxide comprises at least one of LaBaFeO 4 and LaBaCoO 4 .

12. The method as recited in claim 10 , comprising exposing the exhaust gas stream to the layered oxide prior to exposing the exhaust gas stream to the spinel.

13. The method as recited in claim 10 , comprising flowing the exhaust gas stream through the co-catalyst at a temperature less than about 500° C.

14. The method as recited in claim 10 , comprising recirculating the exhaust gas stream through the co-catalyst system.

Assignees

• Toyota Eng & Mfg North America

Inventors

• Peck Torin C
• Rowe Michael Paul
• Jones Michael

Classifications

• B01J35/77

  Compounds characterised by their crystallite size · CPC title

• B01J35/45

  Nanoparticles · CPC title

• B01J2235/00

  Indexing scheme associated with group B01J35/00, related to the analysis techniques used to determine the catalysts form or properties · CPC title

• B01J2235/15

  X-ray diffraction · CPC title

• B01J35/70

  characterised by their crystalline properties, e.g. semi-crystalline (catalysts comprising carbon B01J21/18; molecular sieves B01J29/00) · CPC title